<!DOCTYPE HTML>
 <html>
 <body>
 <canvas id="myCanvas" width="480" height="300" style="border:1px solid #c3c3c3;">
 Your browser does not support the canvas element.
 </canvas>
     <script language="javascript" type="text/javascript" src="./Jscex/src/uglifyjs-parser.js"></script>            
     <script language="javascript" type="text/javascript" src="./Jscex/src/jscex-jit.js"></script>                  
     <script language="javascript" type="text/javascript" src="./Jscex/src/jscex-builderbase.js"></script> 
     <script language="javascript" type="text/javascript" src="./Jscex/src/jscex-async.js"></script>          
     <script language="javascript" type="text/javascript" src="./Jscex/src/jscex-async-powerpack.js"></script>     
 <script type="text/javascript">                                          
     var c = document.getElementById("myCanvas");
     var cxt = c.getContext("2d");
     var x = 150;
     var y = 150;
     var r = 100;
     var drawAsync = eval(Jscex.compile("async", function () {
         cxt.moveTo(x - r, y);
         for (var i = x - r; i < x + r + 1; i++) {
             $await(Jscex.Async.sleep(10));
             var tempY = Math.pow(r * r - (x - i) * (x - i), 1 / 2);
             cxt.lineTo(i, y + tempY);
             cxt.stroke();
         }
         cxt.moveTo(x - r, y);
         for (var i = x - r; i < x + r + 1; i++) {
             $await(Jscex.Async.sleep(10));
             var tempY = Math.pow(r * r - (x - i) * (x - i), 1 / 2);
             cxt.lineTo(i, y - tempY);
             cxt.stroke();
         }
      
     }));
     drawAsync().start();
 </script>

 </body>
 </html>